The E3 ubiquitin-protein ligase MDM2 is a novel interactor of the von Hippel–Lindau tumor suppressor

Abstract

Mutations of the von Hippel–Lindau (pVHL) tumor suppressor are causative of a familiar predisposition to develop different types of cancer. pVHL is mainly known for its role in regulating hypoxia-inducible factor 1 α (HIF-1α) degradation, thus modulating the hypoxia response. There are different pVHL isoforms, including pVHL30 and pVHL19. However, little is known about isoform-specific functions and protein–protein interactions. Integrating in silico predictions with in vitro and in vivo assays, we describe a novel interaction between pVHL and mouse double minute 2 homolog (MDM2). We found that pVHL30, and not pVHL19, forms a complex with MDM2, and that the N-terminal acidic tail of pVHL30 is required for its association with MDM2. Further, we demonstrate that an intrinsically disordered region upstream of the tetramerization domain of MDM2 is responsible for its isoform-specific association with pVHL30. This region is highly conserved in higher mammals, including primates, similarly to what has been already shown for the N-terminal tail of pVHL30. Finally, we show that overexpression of pVHL30 and MDM2 together reduces cell metabolic activity and necrosis, suggesting a synergistic effect of these E3 ubiquitin ligases. Collectively, our data show an isoform-specific interaction of pVHL with MDM2, suggesting an interplay between these two E3 ubiquitin ligases.

Cerebellar Hemangioblastoma with Leptomeningeal Spread and a Fatal Outcome: A Rare Case Report with MDM2 and EGFR Alterations

“…Falconieri et al, predicted that MDM2 is a novel direct interactor of pVHL. 14 To our knowledge, this is the first publication in English literature in which MDM2 gene was analyzed by IHC and FISH in a series of sporadic HB cases (non VHL-related HB) and specifically in a case with a fatal outcome. We found copy-number gains in MDM2 gene by FISH in good concordance with IHC results ( Figure 2D and E ), (Data Availability Statement).…”

Characterization of the pVHL Interactome in Human Testis Using High-Throughput Library Screening

“…The Ubiquitin Specific Peptidase 7 (USP7) is a deubiquitinating enzyme involved in p53 stabilization [ 39 ] presenting high affinity for MDM2, the main E3 ubiquitin-ligase involved in p53 degradation [ 40 ]. pVHL30 was recently proposed to bind MDM2 up-stream to the USP7 interacting motif [ 41 ]. Moreover, pVHL30 is also known to interact with both USP33 and USP20, two enzymes belonging to the USP protein family, whose USP7 is a further member [ 42 ].…”

Characterization of the pVHL Interactome in Human Testis Using High-Throughput Library Screening

“…The Ubiquitin Specific Peptidase 7 (USP7) is a deubiquitinating enzyme involved in p53 stabilization [39] presenting high affinity for MDM2, the main E3 ubiquitin-ligase involved in p53 degradation [40]. The pVHL30 was recently proposed to bind MDM2 up-stream to the USP7 interacting motif [41]. Moreover, pVHL30 is also known to interact with both USP33 and USP20, two enzymes belonging to the USP protein family, whose USP7 is a further member [42].…”